Alcohol intolerance can cause immediate, unpleasant reactions after you drink alcohol. The most common signs and symptoms of alcohol intolerance are stuffy nose and skin flushing. Alcohol intolerance is caused by a genetic condition in which the body is unable to break down alcohol efficiently. The only way to prevent alcohol intolerance reactions is to avoid alcohol.

Alcohol intolerance isn't an allergy. However, in some cases, what seems to be alcohol intolerance may be your reaction to something in an alcoholic beverage — such as chemicals, grains or preservatives. Combining alcohol with certain medications also can cause reactions.

In rare instances, an unpleasant reaction to alcohol can be a sign of a serious underlying health problem that requires diagnosis and treatment.

Signs and symptoms of alcohol intolerance — or of a reaction to ingredients in an alcoholic beverage — can include:

Facial redness (flushing)

Warm, red, itchy bumps on the skin (hives)

Worsening of preexisting asthma

Runny or stuffy nose

Low blood pressure

Nausea and vomiting

Diarrhea

When to see a doctor

You may not need to see a doctor if you have a mild intolerance to alcohol or something else in alcoholic beverages. You may simply need to avoid alcohol, limit how much you drink or avoid certain types of alcoholic beverages. However, if you have a serious reaction or severe pain, see your doctor. Also, if your symptoms seem to be linked to an allergy or a medication you're taking, see your doctor.

Alcohol intolerance occurs when your body doesn't have the proper enzymes to break down (metabolize) the toxins in alcohol. This is caused by inherited (genetic) traits usually found in Asians.

Other ingredients commonly found in alcoholic beverages, especially in beer or wine, can cause intolerance reactions. These include:

Sulfites or other preservatives

Chemicals, grains or other ingredients

Histamine, a byproduct of fermentation or brewing

In some cases, reactions can be triggered by an allergy to a grain such as corn, wheat or rye or to another substance contained in alcoholic beverages.

Rarely, severe pain after drinking alcohol is a sign of a more serious disorder, such as Hodgkin lymphoma.

Risk factors for alcohol intolerance or other reactions to alcoholic beverages include:

Being of Asian descent

Having asthma or hay fever (allergic rhinitis)

Having an allergy to grains or to another food

Having Hodgkins lymphoma

Depending on the cause, complications of alcohol intolerance or other reactions to alcoholic beverages can include:

Migraines. Drinking alcohol can trigger migraines in some people, possibly as a result of histamines contained in some alcoholic beverages. Your immune system also releases histamines during an allergic reaction.

A severe allergic reaction. In rare instances, an allergic reaction can be life-threatening (anaphylactic reaction) and require emergency treatment.

Although alcohol intolerance usually isn't a serious issue, you may want to discuss it with your doctor at your next appointment. Here's some information to help you get ready for your appointment.

Write down your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment.

Write down key personal information, including major stresses or recent life changes. Stress can sometimes worsen allergic reactions or sensitivities.

List all medications, vitamins or supplements you're taking and the dosage.

Write down questions to ask your doctor.

Questions to ask your doctor

What do you think is causing my reaction to alcoholic beverages?

Are any of my medications likely causing or worsening my reaction to alcohol?

Other than the most likely cause, what are other possible causes of my symptoms?

What to expect from your doctor

How long does it take for symptoms to appear after drinking the beverage?

How much of the beverage do you drink before you notice a reaction?

Have you tried over-the-counter allergy medications, such as antihistamines, for your reaction, and if so, did they help?

Are you allergic to particular foods, or to pollens, dust or other airborne substances?

What you can do in the meantime

Avoid the beverage or beverages that seem to cause your reaction until your doctor's appointment. If you do drink a beverage that causes a mild reaction, over-the-counter antihistamines may help relieve symptoms. For a more severe reaction — severe skin reaction, weak pulse, vomiting or trouble breathing — seek emergency help right away.

The following may help your doctor determine the cause of your symptoms and whether you have alcohol intolerance or something else:

Description of your symptoms. Be prepared to describe your symptoms and what drinks cause them. Your doctor may want to know whether you have blood relatives with food allergies or other allergies.

Physical examination. A careful exam can identify or exclude other medical problems.

Skin test. A skin prick test can determine whether you may be allergic to something in alcoholic beverages — for example, grains in beer. Your skin is pricked with a tiny amount of a substance that could be causing your reaction. If you're allergic to the substance being tested, you'll develop a raised bump or other skin reaction.

Blood test. A blood test can measure your immune system's response to a particular substance by checking the amount of allergy-type antibodies in your bloodstream known as immunoglobulin E antibodies. A blood sample is sent to a laboratory to check reactions to certain foods. However, these blood tests aren't always accurate.

The only way to avoid alcohol intolerance symptoms or an allergic reaction is to avoid alcohol or the particular beverage or ingredients that cause the problem. For a minor reaction, over-the-counter or prescription antihistamines may help reduce symptoms, such as itching or hives. However, antihistamines can't treat a serious allergic reaction.

If you've had a severe allergic reaction to a certain food, wear a medical alert bracelet or necklace to let others know you have an allergy, in case you're unable to communicate during a severe reaction. Ask your doctor if you need to carry emergency epinephrine (adrenaline) in the form of an autoinjector (EpiPen, Auvi-Q). This prescription device has a concealed needle that injects a single dose of epinephrine when you press it against your thigh.

Unfortunately, nothing can prevent reactions to alcohol or ingredients in alcoholic beverages. To avoid a reaction, avoid alcohol or the particular substance that causes your reaction.

Read beverage labels to see whether they contain ingredients or additives you know cause a reaction, such as sulfites or certain grains. Be aware, however, that labels may not list all ingredients.

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